Question
I would like to be sure about the high impedance state of a dedicated channel for my power supply unit.
Do you have a process to test and to ensure that? Can you also please explain, how the high impedance mode works?
Hi Impedance Mode for Power Supplies (e.g. NGP800)
Answer
The High Impedance (HI) Mode slows down the discharging after switching off the output port of the PSU.
As there is a capacitor in parallel to the output for hum reduction, we also need to have a discharging resistor.
In HI mode this discharging resistor is enlarged by the additional line impedance after switching off the output.
When measuring the behavior only with a capacitor connected to the output, you can clearly see the difference:
HI Mode (with a nominal 220 µF capacitor connected):
Now the samecapacitor's behavior with HI Mode switched off:
It will end up at a discharging time of about 1ms then.
